This folder contains the C++ source code for the P4-16 compiler. This is a reference implementation of a compiler for the 2016 version of the P4 programming language, also called P4-16. The P4-16 draft spec is available at http://p4.org/wp-content/uploads/2016/12/P4_16-prerelease-Dec_16.html. For the P4 programming language see http://p4.org.

This repository depends on several submodules.

• You can clone p4c and these submodules in one step using the following command: git clone --recursive
• Alternatively, if you've already cloned p4c, you can clone the submodules using the command: git submodule update --init --recursive

The code contains three sample compiler back-ends:

• p4c-bm2-ss: can be used to target the P4 simple_switch written using the BMv2 behavioral model https://github.com/p4lang/behavioral-model
• p4c-ebpf: can be used to generate C code which can be compiled to EBPF https://en.wikipedia.org/wiki/Berkeley_Packet_Filter and then loaded in the Linux kernel for packet filtering
• p4test: a source-to-source P4 translator which can be used for testing, learning compiler internals and debugging.

Some of these compilers can accept both P4-14 (i.e., P4 v1.0, v1.1) and P4-16 programs.

The code and documentation are hosted in the following git repository: https://github.com/p4lang/p4c

The code is currently alpha quality.

We have tested the compiler on U*X systems (MacOS and Ubuntu). The following tools are required to build and run the compiler and tests:

• A C++11 compiler E.g., gcc 4.8 or later, or clang++

• git for version control

• GNU autotools for the build process

• Boehm-Weiser garbage-collector C++ library

• GNU Bison and Flex for the parser and lexical analyzer generators.

• Google Protocol Buffers 3.0 for control plane API generation

• GNU multiple precision library GMP

• C++ boost library (minimally used)

• Python 2.7 for scripting and running tests

• Optional: Documentation generation (enabled when configuring with --enable-doxygen-doc) requires Doxygen (1.8.10 or higher), Graphviz (2.38.0 or higher) and if desired to generate PDF documentation, LaTeX.

The compiler is modular, and it contains multiple back-ends. New ones can be added easily. Each back-end may have additional dependences. This repository contains the following two back-ends; please read the following documents for installing more dependences:

• BMv2
• eBPF

Most dependences can be installed using apt-get install:

sudo apt-get install g++ git automake libtool libgc-dev bison flex libgmp-dev libboost-dev pkg-config python python-scapy python-ipaddr tcpdump

For documentation building: sudo apt-get install -y doxygen graphviz texlive-full

An exception is Google Protocol Buffers; p4c depends on version 3.0, which is not available until Ubuntu 16.10. For earlier releases of Ubuntu, you'll need to install from source. You can find instructions here. Check out the newest tag in the 3.0 series (v3.0.2 as of this writing) before you build.

git checkout v3.0.2

Please note that while newer versions should work for p4c itself, you may run into trouble with some extensions unless you install version 3.0, so you may want to install from source even on newer releases of Ubuntu.

Installing on macOS:

• Enable XCode's command-line tools:

  xcode-select --install
  

• Install Homebrew:

  /usr/bin/ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)"
  

  Be sure to add /usr/local/bin/ to your $PATH.

• Install dependencies using Homebrew:

  brew install autoconf automake libtool bdw-gc boost bison pkg-config
  

  Install GMP built in C++11 mode:

  brew install gmp --c++11
  

  By default, Homebrew doesn't link programs into /usr/local/bin if they would conflict with a version provided by the base system. This includes Bison, since an older version ships with macOS. make check depends on the newer Bison we just installed from Homebrew (see #83), so you'll want to add it to your $PATH one way or another. One simple way to do that is to request that Homebrew link it into /usr/local/bin:

  brew link --force bison
  

  Optional documentation building tools:

  brew install doxygen graphviz
  

  For Latex we recommend MacTeX (http://www.tug.org/mactex/).

  Homebrew offers a protobuf formula. It installs version 3.2, which should work for p4c itself but may cause problems with some extensions. It's preferable to install Protocol Buffers 3.0 from source using the instructions here. Check out the newest tag in the 3.0 series (v3.0.2 as of this writing) before you build.

• We recommend installing a new version of gdb, because older gdb versions do not always handle C++11 correctly. See http://ftp.gnu.org/gnu/gdb.

• We recommend exuberant ctags for navigating source code in Emacs and vi. sudo apt-get install exuberant-ctags. The Makefile targets make ctags and make etags generate tags for vi and Emacs respectively. (Make sure that you are using the correct version of ctags; there are several competing programs with the same name in existence.)

• Steps for setting up Eclipse under Ubuntu Linux 14.04 can be found in Eclipse-readme.

By default the build is performed in a separate folder build.

./bootstrap.sh
cd build
make -j4
make check -j4

To enable building code documentation, please run bootstrap.sh --enable-doxygen-doc. This enables the make docs rule to generate documentation. HTML and PDF (if enabled) are available in build/doxygen-out/html/index.html and build/doxygen-out/p4c.pdf, respectively.

We recommend using clang++ with no optimizations for speeding up compilation and simplifying debugging.

A Dockerfile is included. You can generate an image which contains a copy of p4c in /p4c/build by running:

docker build -t p4c .

On some platforms Docker limits the memory usage of any container, even containers used during the docker build process. On macOS in particular the default is 2GB, which is not enough to build p4c. Increase the memory limit to at least 4GB via Docker preferences or you are likely to see "internal compiler errors" from gcc which are caused by low memory.

More documentation is in docs/README.md